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Message-ID: <1fc9815e-76dd-41d7-aa1a-caa72ef4ad34@linaro.org>
Date: Tue, 23 Jan 2024 13:09:07 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Amrit Anand <quic_amrianan@...cinc.com>, robh+dt@...nel.org,
krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, agross@...nel.org,
andersson@...nel.org, konrad.dybcio@...aro.org
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-msm@...r.kernel.org, kernel@...cinc.com,
Elliot Berman <quic_eberman@...cinc.com>
Subject: Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id
On 20/01/2024 12:20, Amrit Anand wrote:
> From: Elliot Berman <quic_eberman@...cinc.com>
>
>
> How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
> -------------------------------------------------------------
> The selection process for devicetrees was Qualcomm-specific and not
> useful for other devices and bootloaders that were not developed by
> Qualcomm because a complex algorithm was used to implement. Board-ids
> provide a matching solution that can be implemented by bootloaders
> without introducing vendor-specific code. Qualcomm uses three
> devicetree properties: msm-id (interchangeably: soc-id), board-id, and
> pmic-id. This does not scale well for use casese which use identifiers,
> for example, to distinguish between a display panel. For a display
> panel, an approach could be to add a new property: display-id,
> but now bootloaders need to be updated to also read this property. We
> want to avoid requiring to update bootloaders with new hardware
Some mis-indentation in two lines above.
> identifiers: a bootloader need only recognize the identifiers it can
> handle.
>
> Signed-off-by: Elliot Berman <quic_eberman@...cinc.com>
> Signed-off-by: Amrit Anand <quic_amrianan@...cinc.com>
> ---
> .../devicetree/bindings/hwinfo/board-id.yaml | 53 ++++++++++++++++++++++
> 1 file changed, 53 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/hwinfo/board-id.yaml
>
> diff --git a/Documentation/devicetree/bindings/hwinfo/board-id.yaml b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
I think we should add it to dtschema, because bootloaders are using these.
> new file mode 100644
> index 0000000..82d5ff7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
> @@ -0,0 +1,53 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwinfo/board-id.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Board Identifier for Devicetree Selection
> +
> +maintainers:
> + - Amrit Anand <quic_amrianan@...cinc.com>
> + - Elliot Berman <quic_eberman@...cinc.com>
> +
> +description: |
Do not need '|' unless you need to preserve formatting.
> + Device manufacturers frequently ship multiple boards under a single
> + software package. These software packages will ship multiple devicetree
> + blobs and require some mechanism to pick the correct DTB for the board
> + the software package was deployed. board-id provides a mechanism for
> + bootloaders to select the appropriate DTB which is vendor/OEM-agnostic.
> +
> +select:
> + anyOf:
> + - required:
> + - 'board-id'
> + - required:
> + - 'board-id-types'
> + - required:
> + - '#board-id-cells'
I don't fully get why do you need this select. Isn't the schema selected
by nodename? Or maybe it is for the final required: but then this could
be just set of dependencies.
> +
> +properties:
> + $nodename:
> + const: "/"
Blank line.
> + board-id:
> + $ref: /schemas/types.yaml#/definitions/uint32-matrix
> + description: |
Do not need '|' unless you need to preserve formatting.
> + A list of identifiers that can be used to match with this devicetree.
s/devicetree/Devicetree/ ?
> + The interpretatation of each cell can be matched with the
Typo: interpretation
> + board-id-type at the same index.
> +
> + board-id-types:
> + $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> + description:
> + Defines the type of each cell, indicating to the DeviceTree selection
s/DeviceTree/Devicetree/ ?
> + mechanism how to parse the board-id.
> +
> + '#board-id-cells':
What are the cells for?
> + minimum: 1
> +
> +required:
> + - board-id
> + - board-id-types
> + - '#board-id-cells'
> +
> +additionalProperties: true
Best regards,
Krzysztof
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